Calsilica (or Calsilica) is an opaque gem with
colorful stripes/layers of light and dark blue,
green, yellow, orange, red, black and occasionally even
pink. Calsilica is a popular gem and is readily available
as cabochons and carvings.
has been claimed that Calsilica is a natural form of microcrystalline Calcite with layers
various natural clay minerals as the bonding and coloring agents. It is claimed
to be mined in Chihuahua, Mexico were it was allegedly discovered
in the veins or seams of volcanic rhyolite in the mine. Although suppliers claim that
Rainbow Calsilica is a natural stone, tests have indicated
that it is powdered carbonate rock artificially colored and
then stabilized with plastic. It contains a
mixture of Calcite, silica, plastic and artifical coloring pigments such as
art-supply pigment, and a paraffin-like material. [ref: Winter 2002,
Gems and Gemology, journal of the Gemological Institute of America].
the Swiss Gemological Institute ( www.SSEF.ch ) published an article on Calsilica
in their newsletter. SSEF purchased two specimens at a mineral show
in France in 2002. The seller produced photographs of the alleged mine in Mexico along
with an authentication letter from a US laboratory stating that the materials
were not man-made. SSEF's testing found that the base white materials were indeed Calcite.
However, they also found man-made coloring pigments within the specimens.
and that the particles were bonded together by a transparent
soft, plastic-like material that was very similar to paraffin wax.